[PATCH 5/5] lib/raid6: add ARM-NEON accelerated syndrome calculation
Nicolas Pitre
nicolas.pitre at linaro.org
Thu Jun 6 11:55:30 EDT 2013
On Thu, 6 Jun 2013, Ard Biesheuvel wrote:
> Rebased/reworked a patch contributed by Rob Herring that uses
> NEON intrinsics to perform the RAID-6 syndrome calculations.
> It uses the existing unroll.awk code to generate several
> unrolled versions of which the best performing one is selected
> at boot time.
>
> Output captured from an ARM Cortex-A15 @ 1.7 GHz:
>
> raid6: int32x1 200 MB/s
> raid6: int32x2 304 MB/s
> raid6: int32x4 388 MB/s
> raid6: int32x8 423 MB/s
> raid6: neonx1 799 MB/s
> raid6: neonx2 1364 MB/s
> raid6: neonx4 1731 MB/s
> raid6: neonx8 1676 MB/s
> raid6: using algorithm neonx4 (1731 MB/s)
> raid6: using intx1 recovery algorithm
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Acked-by: Nicolas Pitre <nico at linaro.org>
> ---
> include/linux/raid/pq.h | 5 ++++
> lib/raid6/.gitignore | 1 +
> lib/raid6/Makefile | 31 +++++++++++++++++++
> lib/raid6/algos.c | 6 ++++
> lib/raid6/neon.c | 58 +++++++++++++++++++++++++++++++++++
> lib/raid6/neon.uc | 80 +++++++++++++++++++++++++++++++++++++++++++++++++
> lib/raid6/test/Makefile | 19 +++++++++++-
> 7 files changed, 199 insertions(+), 1 deletion(-)
> create mode 100644 lib/raid6/neon.c
> create mode 100644 lib/raid6/neon.uc
>
> diff --git a/include/linux/raid/pq.h b/include/linux/raid/pq.h
> index 8dfaa2c..0f42469 100644
> --- a/include/linux/raid/pq.h
> +++ b/include/linux/raid/pq.h
> @@ -114,6 +114,11 @@ extern const struct raid6_recov_calls raid6_recov_intx1;
> extern const struct raid6_recov_calls raid6_recov_ssse3;
> extern const struct raid6_recov_calls raid6_recov_avx2;
>
> +extern const struct raid6_calls raid6_neonx1;
> +extern const struct raid6_calls raid6_neonx2;
> +extern const struct raid6_calls raid6_neonx4;
> +extern const struct raid6_calls raid6_neonx8;
> +
> /* Algorithm list */
> extern const struct raid6_calls * const raid6_algos[];
> extern const struct raid6_recov_calls *const raid6_recov_algos[];
> diff --git a/lib/raid6/.gitignore b/lib/raid6/.gitignore
> index 162beca..0a7e494 100644
> --- a/lib/raid6/.gitignore
> +++ b/lib/raid6/.gitignore
> @@ -2,3 +2,4 @@ mktables
> altivec*.c
> int*.c
> tables.c
> +neon?.c
> diff --git a/lib/raid6/Makefile b/lib/raid6/Makefile
> index 9f7c184..6a51f1a 100644
> --- a/lib/raid6/Makefile
> +++ b/lib/raid6/Makefile
> @@ -5,6 +5,7 @@ raid6_pq-y += algos.o recov.o tables.o int1.o int2.o int4.o \
>
> raid6_pq-$(CONFIG_X86) += recov_ssse3.o recov_avx2.o mmx.o sse1.o sse2.o avx2.o
> raid6_pq-$(CONFIG_ALTIVEC) += altivec1.o altivec2.o altivec4.o altivec8.o
> +raid6_pq-$(CONFIG_KERNEL_MODE_NEON) += neon.o neon1.o neon2.o neon4.o neon8.o
>
> hostprogs-y += mktables
>
> @@ -16,6 +17,12 @@ ifeq ($(CONFIG_ALTIVEC),y)
> altivec_flags := -maltivec -mabi=altivec
> endif
>
> +# The GCC option -ffreestanding is required in order to compile code containing
> +# ARM/NEON intrinsics in a non C99-compliant environment (such as the kernel)
> +ifeq ($(CONFIG_KERNEL_MODE_NEON),y)
> +NEON_FLAGS := -mfloat-abi=softfp -mfpu=neon -ffreestanding
> +endif
> +
> targets += int1.c
> $(obj)/int1.c: UNROLL := 1
> $(obj)/int1.c: $(src)/int.uc $(src)/unroll.awk FORCE
> @@ -70,6 +77,30 @@ $(obj)/altivec8.c: UNROLL := 8
> $(obj)/altivec8.c: $(src)/altivec.uc $(src)/unroll.awk FORCE
> $(call if_changed,unroll)
>
> +CFLAGS_neon1.o += $(NEON_FLAGS)
> +targets += neon1.c
> +$(obj)/neon1.c: UNROLL := 1
> +$(obj)/neon1.c: $(src)/neon.uc $(src)/unroll.awk FORCE
> + $(call if_changed,unroll)
> +
> +CFLAGS_neon2.o += $(NEON_FLAGS)
> +targets += neon2.c
> +$(obj)/neon2.c: UNROLL := 2
> +$(obj)/neon2.c: $(src)/neon.uc $(src)/unroll.awk FORCE
> + $(call if_changed,unroll)
> +
> +CFLAGS_neon4.o += $(NEON_FLAGS)
> +targets += neon4.c
> +$(obj)/neon4.c: UNROLL := 4
> +$(obj)/neon4.c: $(src)/neon.uc $(src)/unroll.awk FORCE
> + $(call if_changed,unroll)
> +
> +CFLAGS_neon8.o += $(NEON_FLAGS)
> +targets += neon8.c
> +$(obj)/neon8.c: UNROLL := 8
> +$(obj)/neon8.c: $(src)/neon.uc $(src)/unroll.awk FORCE
> + $(call if_changed,unroll)
> +
> quiet_cmd_mktable = TABLE $@
> cmd_mktable = $(obj)/mktables > $@ || ( rm -f $@ && exit 1 )
>
> diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c
> index 6d7316f..74e6f56 100644
> --- a/lib/raid6/algos.c
> +++ b/lib/raid6/algos.c
> @@ -70,6 +70,12 @@ const struct raid6_calls * const raid6_algos[] = {
> &raid6_intx2,
> &raid6_intx4,
> &raid6_intx8,
> +#ifdef CONFIG_KERNEL_MODE_NEON
> + &raid6_neonx1,
> + &raid6_neonx2,
> + &raid6_neonx4,
> + &raid6_neonx8,
> +#endif
> NULL
> };
>
> diff --git a/lib/raid6/neon.c b/lib/raid6/neon.c
> new file mode 100644
> index 0000000..dad7102
> --- /dev/null
> +++ b/lib/raid6/neon.c
> @@ -0,0 +1,58 @@
> +/*
> + * linux/lib/raid6/neon.c - RAID6 syndrome calculation using ARM NEON intrinsics
> + *
> + * Copyright (C) 2013 Linaro Ltd <ard.biesheuvel at linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/raid/pq.h>
> +
> +#ifdef __KERNEL__
> +#include <asm/neon.h>
> +#else
> +#define kernel_neon_begin()
> +#define kernel_neon_end()
> +#define cpu_has_neon() (1)
> +#endif
> +
> +/*
> + * There are 2 reasons these wrappers are kept in a separate compilation unit
> + * from the actual implementations in neonN.c (generated from neon.uc by
> + * unroll.awk):
> + * - the actual implementations use NEON intrinsics, and the GCC support header
> + * (arm_neon.h) is not fully compatible (type wise) with the kernel;
> + * - the neonN.c files are compiled with -mfpu=neon and optimization enabled,
> + * and we have to make sure that we never use *any* NEON/VFP instructions
> + * outside a kernel_neon_begin()/kernel_neon_end() pair.
> + */
> +
> +#define RAID6_NEON_WRAPPER(_n) \
> + static void raid6_neon ## _n ## _gen_syndrome(int disks, \
> + size_t bytes, void **ptrs) \
> + { \
> + void raid6_neon ## _n ## _gen_syndrome_real(int, \
> + unsigned int, void**); \
> + kernel_neon_begin(); \
> + raid6_neon ## _n ## _gen_syndrome_real(disks, \
> + (unsigned int)bytes, ptrs); \
> + kernel_neon_end(); \
> + } \
> + struct raid6_calls const raid6_neonx ## _n = { \
> + raid6_neon ## _n ## _gen_syndrome, \
> + raid6_have_neon, \
> + "neonx" #_n, \
> + 0 \
> + };
> +
> +static int raid6_have_neon(void)
> +{
> + return cpu_has_neon();
> +}
> +
> +RAID6_NEON_WRAPPER(1)
> +RAID6_NEON_WRAPPER(2)
> +RAID6_NEON_WRAPPER(4)
> +RAID6_NEON_WRAPPER(8)
> diff --git a/lib/raid6/neon.uc b/lib/raid6/neon.uc
> new file mode 100644
> index 0000000..f2d7ec0
> --- /dev/null
> +++ b/lib/raid6/neon.uc
> @@ -0,0 +1,80 @@
> +/* -----------------------------------------------------------------------
> + *
> + * neon.uc - RAID-6 syndrome calculation using ARM NEON instructions
> + *
> + * Copyright (C) 2012 Rob Herring
> + *
> + * Based on altivec.uc:
> + * Copyright 2002-2004 H. Peter Anvin - All Rights Reserved
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
> + * Boston MA 02111-1307, USA; either version 2 of the License, or
> + * (at your option) any later version; incorporated herein by reference.
> + *
> + * ----------------------------------------------------------------------- */
> +
> +/*
> + * neon$#.c
> + *
> + * $#-way unrolled NEON intrinsics math RAID-6 instruction set
> + *
> + * This file is postprocessed using unroll.awk
> + */
> +
> +#include <arm_neon.h>
> +
> +typedef uint8x16_t unative_t;
> +
> +#define NBYTES(x) ((unative_t){x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x})
> +#define NSIZE sizeof(unative_t)
> +
> +/*
> + * The SHLBYTE() operation shifts each byte left by 1, *not*
> + * rolling over into the next byte
> + */
> +static inline unative_t SHLBYTE(unative_t v)
> +{
> + return vshlq_n_u8(v, 1);
> +}
> +
> +/*
> + * The MASK() operation returns 0xFF in any byte for which the high
> + * bit is 1, 0x00 for any byte for which the high bit is 0.
> + */
> +static inline unative_t MASK(unative_t v)
> +{
> + const uint8x16_t temp = NBYTES(0);
> + return (unative_t)vcltq_s8((int8x16_t)v, (int8x16_t)temp);
> +}
> +
> +void raid6_neon$#_gen_syndrome_real(int disks, unsigned int bytes, void **ptrs)
> +{
> + uint8_t **dptr = (uint8_t **)ptrs;
> + uint8_t *p, *q;
> + int d, z, z0;
> +
> + register unative_t wd$$, wq$$, wp$$, w1$$, w2$$;
> + const unative_t x1d = NBYTES(0x1d);
> +
> + z0 = disks - 3; /* Highest data disk */
> + p = dptr[z0+1]; /* XOR parity */
> + q = dptr[z0+2]; /* RS syndrome */
> +
> + for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
> + wq$$ = wp$$ = vld1q_u8(&dptr[z0][d+$$*NSIZE]);
> + for ( z = z0-1 ; z >= 0 ; z-- ) {
> + wd$$ = vld1q_u8(&dptr[z][d+$$*NSIZE]);
> + wp$$ = veorq_u8(wp$$, wd$$);
> + w2$$ = MASK(wq$$);
> + w1$$ = SHLBYTE(wq$$);
> +
> + w2$$ = vandq_u8(w2$$, x1d);
> + w1$$ = veorq_u8(w1$$, w2$$);
> + wq$$ = veorq_u8(w1$$, wd$$);
> + }
> + vst1q_u8(&p[d+NSIZE*$$], wp$$);
> + vst1q_u8(&q[d+NSIZE*$$], wq$$);
> + }
> +}
> diff --git a/lib/raid6/test/Makefile b/lib/raid6/test/Makefile
> index 087332d..bbe6450 100644
> --- a/lib/raid6/test/Makefile
> +++ b/lib/raid6/test/Makefile
> @@ -34,6 +34,11 @@ else
> ifeq ($(HAS_ALTIVEC),yes)
> OBJS += altivec1.o altivec2.o altivec4.o altivec8.o
> endif
> + ifeq ($(ARCH),arm)
> + CFLAGS += -I../../../arch/arm/include -mfpu=neon \
> + -DCONFIG_KERNEL_MODE_NEON=1
> + OBJS += neon.o neon1.o neon2.o neon4.o neon8.o
> + endif
> endif
>
> .c.o:
> @@ -55,6 +60,18 @@ raid6.a: $(OBJS)
> raid6test: test.c raid6.a
> $(CC) $(CFLAGS) -o raid6test $^
>
> +neon1.c: neon.uc ../unroll.awk
> + $(AWK) ../unroll.awk -vN=1 < neon.uc > $@
> +
> +neon2.c: neon.uc ../unroll.awk
> + $(AWK) ../unroll.awk -vN=2 < neon.uc > $@
> +
> +neon4.c: neon.uc ../unroll.awk
> + $(AWK) ../unroll.awk -vN=4 < neon.uc > $@
> +
> +neon8.c: neon.uc ../unroll.awk
> + $(AWK) ../unroll.awk -vN=8 < neon.uc > $@
> +
> altivec1.c: altivec.uc ../unroll.awk
> $(AWK) ../unroll.awk -vN=1 < altivec.uc > $@
>
> @@ -89,7 +106,7 @@ tables.c: mktables
> ./mktables > tables.c
>
> clean:
> - rm -f *.o *.a mktables mktables.c *.uc int*.c altivec*.c tables.c raid6test
> + rm -f *.o *.a mktables mktables.c *.uc int*.c altivec*.c neon*.c tables.c raid6test
>
> spotless: clean
> rm -f *~
> --
> 1.8.1.2
>
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